Learning Outcomes

In this tutorial, we will learn:

  • How to setup Git in our Linux workstation.
  • How to push C codes from our workstation to our Gitlab’s repository using Git.

Why we need to learn this?

Imagine you are part of a large team which works on a software project. How you are going to keep track of the changes you and your team members have made over time? This is when a version control system like Git comes into handy. Git allows us to manage these ever-changing projects by storing the information about these projects in the data structure called a repository.

In this tutorial, we are going to use Git along with Gitlab, a web-based Git repository. Gitlab allows a team of software developers to manage a single software project from anywhere on the earth, as long as they have Internet access. However, bear in mind that it is still possible to manage a software project with Git without a web-based repository and Internet access. You can read more about this here.

Requirements

  • Ubuntu (Mine is 18.04.4 LTS, check yours with the command cat /etc/os-release)
  • CLion (An IDE for C++ and C by JetBrains)
  • Git. It can be installed using the following commands: 
    sudo apt-add-repository ppa:git-core/ppa
sudo apt-get update
sudo apt-get install git
  • xclip for retrieving SSH keys. To install xclip, we can run: 
    sudo apt install xclip
  • Gitlab. Create an account here.

Once we have all these ready, then we are good to go!

Setting up Git

First, check if we have Git installed by typing the following command in our terminal:

Git version

The command tells us which Git version we have on our workstation. If you don’t receive a Git version message, it means that you need to install Git (check on the Requirements section). Next, we need to configure our Git username and email address, since every Git commit will use this information to identify us as the author.

Add our Git username and email by using the following commands:

git config --global user.name "[your_username]"
git config --global user.email "[your_email_address]@[yourdomain].com"

Generating a SSH key pair for our Gitlab account

Open a new terminal on Linux and generate a new ED25519 SSH key pair:

ssh-keygen -t ed25519 -C "[your_email_address]@[yourdomain].com"

ED25519 is the most recommended public-key algorithm available today! You can read more about it here.

We will be asked to input a file path to save our SSH key pair and a passphrase to secure our new SSH key pair. Both of these can be ignored by pressing ENTER. If we did this correctly, we will get multiple messages, telling us where our identification and public key have been saved. We will also get our key fingerprint and our key’s randomart image.

Your identification has been saved in ~/.ssh/id_ed25519.
Your public key has been saved in ~/.ssh/id_ed25519.pub.
The key fingerprint is:
SHA256:XXX [your_email_address]@[yourdomain].com
The key's randomart image is:
+--[ED25519 256]--+
|     .*=XXo      |
|     .oOO=o      |
|     .+o+o       |
|   .o..=o.       |
|  E o*.oS.       |
|   .+.+ .        |
|  . o=           |
|.+ o.o.          |
|* o++..          |
+----[SHA256]-----+

Adding our SSH key pair into the Gitlab account

To retrieve our SSH key pair, we first need to save the key pair into a text file using xclip:

xclip -sel clip < ~/.ssh/id_ed25519.pub -o > ~/gitlabsshkeypair.txt

Now, add the SSH key pair into our Gitlab account by following these steps:

  1. Open the gitlabsshkeypair.txt and copy our SSH key pair.
  2. Open the Gitlab account in a browser, click the Gitlab avatar in the upper right corner and select Settings.
  3. Navigate to SSH Keys and paste the SSH key pair which we have copied to the Key field.
  4. Fill in the Title text box. It can be anything we like. We can leave the Expires at text box empty.
  5. Click the Add key button.

Testing that everything is set up correctly

Let’s test if everything is set up correctly by typing the following line into our terminal:

ssh -T git@gitlab.com

Since it is the first time we connect to Gitlab via SSH, we will be asked to verify the authenticity of the GitLab host we are connecting to. We are supposed to get a message as follow:

The authenticity of host 'gitlab.com (xxx.xxx.xxx.xxx)' can't be established.
ECDSA key fingerprint is SHA256:XXXX.
Are you sure you want to continue connecting (yes/no)?

Type yes. We will get a warning message followed by a welcome message:

Warning: Permanently added 'gitlab.com (xxx.xxx.xxx.xxx)' (ECDSA) to the list of known hosts.
Welcome to GitLab, [your_Gitlab_username]!

By now, we can push and pull codes between our workstation and Gitlab securely!

Push our project from our workstation to Gitlab

We are going to push our codes from the our workstation to our Gitlab account. In order to do this, we first need to have:

  1. A project created in our workstation. In my case, I have a C Executable project created using CLion IDE and stored in the following directory: ~/CLionProjects/CProject.
  2. An empty project created in our Gitlab account, where we are going to push the project’s codes from our workstation into this empty project.

We can create a project in Gitlab account by following these steps:

  1. Clik the New Project button in the upper right corner of our Gitlab account.
  2. Give a name to our project (I used CProject) and click on Create Project.
  3. We will be redirected to the project page. This project should be empty.

Now, go back to our workstation and go to the directory where we saved our project. First, we need to use the init command for Git to begin tracking the directory:

cd ~/CLionProjects/CProject
git init

Note that your directory can be different than mine.

Finally, use the following commands to push our project:

git remote add origin git@gitlab.com:[yourGitLabUsername]/[yourprojectname].git
git add .
git commit -m "Initial commit"
git push -u origin master

In my case, I used git remote add origin git@gitlab.com:you3quan2/cproject.git.

Go to our Gitlab account and we are supposed to see the same set of codes in our workstation’s project folders and the Gitlab’s project folders.

Update changes in our workstation to Gitlab

Now, we have the exact same project in our workstation and Gitlab. But, we still need to update the Gitlab’s project every time we made changes on the project in our workstation. I will show you an example how we can do this.

In my C project, there is a main.c file which contains the following codes:

#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

I updated my main.c file and changed the line from Hello, World! to Goodbye, World!:

#include <stdio.h>

int main() {
    printf("Goodbye, World!\n");
    return 0;
}

Note: You can make changes in any files you like within your project.

To update these changes to my Gitlab project, I used:

git add .
git commit -m "COMMENT TO DESCRIBE THE INTENTION OF THE COMMIT"
git push origin master

My comment is Change from Hello World to Goodbye World.

Go to the Gitlab account and check on the specific file which we have modified. We are supposed to see the changes which we have made. If we click on the History button, we will see our commit changes:

Takeaways

I hope by now you know how to setup your Linux workstation and Gitlab in order for you to push your project from your workstation to Gitlab using Git.

I hope you found this tutorial helpful. Have more questions about this? Let me know by commenting below!

References